(1) Field of the Invention
This invention relates generally to display drivers and relates more specifically to passively segmented Electronic Paper Display (EPD) drivers.
(2) Description of the Prior Art
Electronic paper, e-paper, or electronic ink display is a display technology designed to mimic the appearance of ordinary ink on paper. Unlike a conventional flat panel display, which uses a backlight to illuminate its pixels, electronic paper reflects light like ordinary paper and is capable of holding text and images indefinitely without drawing electricity, while allowing the image to be changed later.
To build e-paper, several different technologies exist, some using plastic substrate and electronics so that the display is flexible. E-paper is considered more comfortable to read than conventional displays. This is due to the stable image, which does not need to be refreshed constantly, the wider viewing angle, and the fact that it reflects ambient light rather than emitting its own light. An e-paper display can be read in direct sunlight without the image fading. Lightweight and durable, e-paper can currently provide color display. The contrast ratio in available displays might be described as similar to that of newspaper.
Currently passive segmented Electronic Paper Display (EPD) drivers as e.g. Solomon Systech Limited Tri-Level Generic Display Driver SSD1623 require the image data to be displayed to be generated by a controller microprocessor. As example, for a prior art bi-level EPD driver a host processor has to generate a complete drive waveform by combining OLD/NEW data with phase/delay waveform requirements.
Other newer EPD drivers contain some internal One Time Programmable (OTP) non-volatile memory to store the phase/delay waveform but require the OLD/NEW data to be loaded from the host processor in order to generate complete the complete drive waveform
It is a challenge for the designers of EPD drivers to remove the requirement for host processors to store display images and/or display image decodes of numerical data, to simplify the process required to construct the display image from stored bitmaps, and to providing pre-programmed multiple phase tables (phase/delay waveform definitions, which allow a simple mechanism to alter the waveform generation.
Solutions dealing with EPD drivers are described in the following patents:
U.S. Patent Application Publication (US 2009/0109468 to Barclay et al.) discloses a portable paperless electronic printer for displaying a printed document on an electronic paper display. The paperless electronic printer includes an input to receive print data from an output of a printer driver of a computerized electronic device, a non-volatile electrophoretic display to provide an electronic paper display of stored said print data for a said document page to mimic said document page when printed on paper; and a processor coupled to said input, to non-volatile memory, and to said non-volatile electrophoretic display and configured to input said print data, to store said data derived from said print data in said non-volatile memory, and to provide to said non-volatile electrophoretic display data for displaying a said document page derived from said stored data.
U.S. patent (U.S. Pat. No. 6,906,705 to Matsuo et al.) proposes providing an electronic paper file with high operating performance. The electronic paper file is assumed to comprises an electronic paper of a flexible display medium and a cover to which a plurality of electronic papers is attachable. In the invention, the first storage means stores display-data to be displayed on the electronic paper. The first display control means obtains from the first storage means the display-data corresponding to the desired page selected by the page selecting means and then display them on the electronic paper. Accordingly, even if the enormous pages of the electronic paper were not attached to the electronic paper file, the invention can display the whole of mass data such as an encyclopedia or theses data. Therefore, it is possible to improve the operating performance of the electronic paper file.
U.S. Patent Application (US 2004/0041785 to Stevens et al.) proposes electronic paper methods and systems. In accordance with one embodiment, an electronic paper driver is provided and is configured to receive a document in a first format from an application and convert the document in the first format to a second format that can be used for rendering a display on electronic paper.
Furthermore the data sheet of Tri-Level Generic Display Driver SSD1623 from Solomon Systech Limited describes a CMOS generic driver with controller. SD1623 is equipped with SPI interface with hardware address map setting pin, allowing two or more SSD1623 connected to same SPI bus, increasing the available number of segments.